Process of making oil traps for vacuum pumps and similar articles



Feb. 16, 1932. E. BANDOLY ,8

PROCESS OF MAKING OIL TRAPS FOR VACUUM PUMPS AND SIMILAR ARTICLES nal Filed April 9. 1926 2 Sheets-Sheet 1 Feb. 16, 1932; E. BANDOLY- CESS OF MAKING OIL TRAPS FOR VACUUM PUMPS AND SIMILAR ARTICLES "PRO '2 Sheets-Sheet 2 Original Filed April 9. 1926 Patented Feb. 16, 1932 UNITED STATES PATENT; "OFFICE ERIGH BANDOLY, OF CHICAGO, ILLINOIS, ASSIGNOR TO CENTRAL SCIENTIFIC COMPANY,

OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS PROCESS OF MAKING OIL TRAPS FOR VACUUM PUMPS AND SIMILAR ARTICLES Original application filed April- 9, 1926,

This invention relates to the manufacture of oil traps for vacuum pumps and similar articles, and has for its principal object to provide a simple and economical process of 5 making them impervious to fluids.

Further objects and advantages of the invention will become apparent as the description is read in connection with the accompanying drawings, in which ig. 1 is a sectional view through an eccentric pump and oil bath taken along the axis of the driving shaft;

Fig. 2 is a similar section taken on the line 22 of Fig. 1; 1

Fig. 3 is a section of the oil trap takenon the line 3-3 of Fig. 1;

Fig. 4 is an elevation of the inside face of the removable wall of the oil bath casing, and

Fig. 5 is a view similar to Fig.' 1, illustrating a modified construction of oil trap and oil bath. F

But these specific illustrations andv corresponding specific descriptions are used to makethe invention clear and .are not intended to require a limitation of the claims 4 other than is made necessary by the prior art.

The apparatus illustrated includes an oil bath generally indicated by A and an eccentric pump generally indicated by B and mounted in the bath.

The pump is of the eccentric type including two units, each composed of a cylinder 10, an eccentric rotor 11, driven by a shaft 12 .mounted concentric with'the cylinder and a blade 13 (Fig. 2) reciprocating in a slot 14 in the cylinder wall and contacting with the outer surface of the rotor 11.

In order to facilitate the assembly of the pump with the bath and the support of the pump therein, one wall 31 (Fig. 1)' of the bath casing is made readily removable and equipped with fastenings for securing the pump to it. The remainder of the bath casing is made in one piece comprising a bottom 32 and sides 33, 34 and 35, each side havin an inturned flange 36 which, together are a apted to receive a removable cover 37.

The upper ortion of the removable wall is formed hol ow to provide a trap oham-' ber 38 which is connected with the inlet passage 28 at the bottom and equipped with a hose nipple 39 by which the pump may be connected with the vessel to be exhausted.

In the form shown in Fig. 1 the bath is made of aluminum die casting and the chamber 38 is provided with a lining shell of steel Serial No. 100,901. Divided and this application filed January 17, 1929. Serial No. 833,249.

composed of a cup-shaped element 40, a disk 41 closing its open side,'and a reenforcing strut 42 bent back and forth as indicated in Fig. 3, and lying between the opposite sides of the chamber. A short piece of steel tubing 43 extends from the inner side of the chamber to the outer face of the plate 15. A sealing cup 44 has a shouldered neck 45 extending through the lining and the aluminum and threaded to receive the hose nipple 39. Y

In practice, the reenforcement is/,welded' at a few points to the disk 41 and the disk 41 is welded to the rim of the cup 40, the tubing 43 and the sealing cup 44 are welded to the disk and the cup in the position shown. This assembly forms an insert which is placed in the molding die and about which the jacket of aluminum, .zinc, alloy, or other light metal is cast.

The steel liner makes the trap mercury proof and in the majority of cases will make.

it also air tight. However, to insure uniformly air tight structures in production the pores should be sealed with a substance having a vapor pressure below any pressure which the pump will be called upon to produce. Certain japans have a vapor pressure of 1/100 of a micron at 110 C. and these are suitable for impregnating the trap.

The sealing process is accomplished in the following. manner :Plug the tubing; screw the cups 44 onto the nipples of a manifold connected with a vacuum pump; exhaust the trap chambers and submerge the castings in liquid japan; continue the submerging until the atmospheric pressure has had an ample opportunity to force the japan into the minute pores; remove and bake to solidify the japan; immerse again without exhausting equipped with a marginal flange 47 termisubstance temporarily liquid, the vapor presnating in alignment with the inner face of sure of which in a solid state is below the the upper portion; this face 48 and the corresponding face of the flange 47 are ground to cooperate with the ground face 49 of the plate 15 to form a proper joint.

The plate 15 is extended beyond the margins of the cylinder 10, as indicated at 50,

(Fig 2) and drilled and tapped to receive studs 51 by which the pump is secured to the wall 31, the latter being thickened at 52 and drilled and tapped to receive the studs.

The removable wall is also thickened and drilled at 54 to receive studs which thread into tapped openings in the body of the bath and secure the removable wall in place.

The lower portion 46 of the wall 31 is provided with a boss 55 aligned with a brass insert 56, which, together with the gland 57 and packing 58, forms a stufling box for the shaft 12.

When the bath is made of cast iron the res. movable wall 60 (Fig. 5) is formed with a trap chamber 61 without any lining, corresponding to that shown in Figs. 1 and 3. Any pores in the walls of this chamber may be sealed by the procedure described above.

This application is a division of my application Serial No. 100,901 filed .April 9, 1926.

I claim as my invention:

1. The process of closing the pores of hollow metallic traps for vacuum pumps which includes creating a pressure differential between the exterior and interior surfaces of the article, applying a temporarily liquid filler to the surface subjected to the higher pressure, and maintaining the pressure differential a sufficient length of time to permit the filler to occupy the pores.

2. The process of closing the pores of hollow metallic oil traps for vacuum pumps which includes reducing the pressure on the interior of the trap, applying a temporarily liquid filler to the exterior of the trap and maintaining the reduction in pressure on .the interior a sufficient len h of time to permit the filler to occupy t e pores.

3. The process of closing the pores of hollow metal articles designed to enclose a vacuous space, which includes creating a pressure differential between the exterior and lnterior surfaces of the articles, ap lying a temporaril liquid filler to the surface sub jected to t e higher pressure and maintainmg the pressure difierential a suflicient length of time to permit the filler to occupy the pores.

4. In the treatment of metallic parts to be subjected to vacuum, that method of rendermg the parts impervious to difi'usious of gases therethrough which consists in subjecting one side of the metallic part to a vacuum of substantial degree, covering the part, with the vacuum still applied, with a order of vacuum to which the said metallic part will be subjected, and continuing such treatment until the voids in the metal are filled.

5. That method of rendering oil traps for vacuum pumps impervious to the diffusion of gases through the material of said trap, which consists in subjecting one side of the trap to a vacuum of substantial degree, cov- F ering the part, with the vacuum still applied, with a substance temporarily liquid, the vapor pressure of which does not exceed the vapor pressure of the sealing fluid to be used in said trap, continuing such process until the voids in the substance of the trap are filled, and subsequently treating said trap to change the filler material to a solid substance.

6. That method of rendering oil traps for vacuum pumps impervious to the diffusion of gases through the material of said trap which consists in subjecting one side of the trap to a vacuum of substantial degree covering the part, with the vacuum still applied, with a substance temporarily liquid, the vapor of which in a solid state does not exceed the lowest pressures which can be produced by the pump, continuing such process until the voids in the substance of the trap are filled, subsequently treating the trap to change the filling material into a solid substance, and then coating the trap with the same filling material and treating to change the coating into a solid substance.

In testimony whereof I afiix my signature.

ERICH BANDOLY. 

